chore(updater): common GetServers signature

- Log warnings when running outside of CLI mode
- Remove updater CLI bool setting
- Warnings are logged in updating functions

internal/provider/protonvpn/updater/updater.go

@@ -0,0 +1,21 @@
+package protonvpn
+
+import (
+	"net/http"
+)
+
+type Updater struct {
+	client *http.Client
+	warner Warner
+}
+
+type Warner interface {
+	Warn(s string)
+}
+
+func New(client *http.Client, warner Warner) *Updater {
+	return &Updater{
+		client: client,
+		warner: warner,
+	}
+}